Historically, hydrocarbons such as oil and gas were produced by drilling a substantially vertical well bore from a surface location above the formation to the desired hydrocarbon zone at some depth below the surface. However, modern drilling technology and techniques allow for the drilling of well bores that deviate from vertical. Therefore, deviated well bores may be drilled from a convenient surface location to the desired hydrocarbon zone.
During such drilling or other well bore operations, it may be economically infeasible or otherwise undesirable to use jointed drill pipe. Therefore, apparatus and methods have been developed for performing such operations using coiled tubing, which is a single length of continuous, unjointed tubing spooled onto a reel for storage in sufficient quantities to exceed the length of the well bore. The coiled tubing may include one or more umbilicals disposed therein, such as a wireline to provide power and data communications to and from a drilling assembly, a hose for injecting chemicals into the well bore, or a heating string, for example.
When drilling a vertical well bore or a sidetracked well bore using a coiled tubing drill string, many circumstances can arise where it becomes necessary to cut the coiled tubing and remove it from the well bore. This may occur, for example, when the drilling assembly gets stuck during drilling, and the coiled tubing must be cut away from the drilling assembly to facilitate fishing, jarring, or other operations.
Under such circumstances, the coiled tubing that extends into the well bore, as well as any umbilicals installed therein, must be cut away from the coiled tubing reel at the surface and released into the well bore. Then, various apparatus and methods are available for cutting the coiled tubing drill string from the drilling assembly and retrieving it from the well bore. One such apparatus comprises a coiled tubing cutter, such as the Cutting Overshot device sold by Thru-Tubing Technology, Inc. of Scott, La. In operation, the Cutting Overshot device is attached to a work string and then lowered to receive the coiled tubing within a tubular housing of the device. When the Cutting Overshot device reaches the desired cutting location on the coiled tubing, the work string is raised to apply an upward force on the Cutting Overshot device, thereby shearing a plurality of set screws, and forcing a cutting grapple into the coiled tubing to cut the tubing. Although the Cutting Overshot device is very effective for cutting the coiled tubing drill string, it is not configured to cut a wireline or other umbilical running inside the coiled tubing. Therefore, at least a second trip into the well bore is required to retrieve and/or cut the wireline and other umbilicals.
There are other circumstances in which a wireline might be stuck within a coiled tubing string in a well bore. For example, a wireline may be used as a work string to lower a cutting device into the coiled tubing that is stuck in the well bore. However, if the wireline cutting device fails, and/or the wireline will not release, the wireline may break, thereby leaving both the stuck coiled tubing with the stuck wireline disposed therein in the well. Under this scenario, a first trip would be made to cut the coiled tubing, such as with the Cutting Overshot device described above, and then a second trip would be made to cut the wireline. Thus, a need exists for apparatus and methods to cut both a coiled tubing and a wireline disposed therein in one trip into the well bore.
There are also circumstances wherein a wireline not associated with a coiled tubing string may be stuck in a well bore, such as when conducting a wireline fishing operation to retrieve a drilling assembly or other downhole tool. In this type of operation, after the coiled tubing has been cut and retrieved from the well bore, a wireline work string is lowered into the well bore with a fishing device disposed at the lower end thereof for catching the drilling assembly or other tool that is stuck in the well bore. However, if the fishing device catches the fish, but the wireline cannot pull it loose, the wireline may break. Then another trip would be required to cut the wire and retrieve it.
Conventionally, fishing tools, such as a wire grab or a rope spear, for example, with barbs disposed on the end thereof, have been used to cut and/or retrieve a wireline that is either stuck in the well bore or simply disconnected from the surface. The fishing tool is run into the well bore past the upper end of the wireline, then rotated to wrap the tool around the wireline and grab the wireline with the barbs. The wireline may also be “bird nested” by pushing it down within the well bore before rotating the fishing tool to thereby tangle the wireline and make it easier to grab with the barbs. Once the wireline has been grabbed by the fishing tool, an upward force is exerted on the fishing tool to either retrieve an unstuck wireline or cut a stuck wireline. However, a need exists for apparatus and methods that will efficiently and effectively cut through a wireline within a well bore.